Security

Security Objectives

Secrecy

Prevent/detect/deter improperDisclosure of information

Availability

Prevent/detect/deter improperDenial of access to services

IntegrityPrevent/detect/deter Improper modificationof information

PolicyOrganizational policyOrganizational policy

Information systems policyInformation systems policy

Security Overview

Many fears to overcomeIntercepted e-mail messagesUnauthorized access to digital intelligenceCredit card information falling into the wrong

handsTwo types of computer security

Physical - protection of tangible objectsLogical - protection of non-physical objects

What is security?

Dictionary Definition: protection or defense against attack, interference, espionage, etc

System correctnessGood input Good output

SecurityBad input Bad output

Goals of Security

DATA

Integrity

DATA

Availability

DATA

Confidentiality

Aspects of Security

consider 3 aspects of information security:security attacksecurity mechanism (control)security service

note termsthreat – a potential for violation of securityvulnerability – a way by which loss can

happenattack – an assault on system security, a

deliberate attempt to evade security services

Computer Security Classification

SECURITY SERVICESSECURITY SERVICES

DATA

CONFIDENTIALITY

DATA

CONFIDENTIALITY

DATA

INTEGRITY

DATA

INTEGRITY

AUTHENTICATIONAUTHENTICATION

NONREPUDIATIONNONREPUDIATION

ACCESS CONTROLACCESS

CONTROL

Computer Security Classification

1. ENCIPHERMENT

2. DATA INTEGRITY

3. DIGITAL SIGNATURE

4. AUTHENTICATION

EXCHANGE

5. TRAFFIC PADDING

6. ROUTING CONTROL

7. NOTARIZATION

8. ACCESS CONTROL

1. ENCIPHERMENT

2. DATA INTEGRITY

3. DIGITAL SIGNATURE

4. AUTHENTICATION

EXCHANGE

5. TRAFFIC PADDING

6. ROUTING CONTROL

7. NOTARIZATION

8. ACCESS CONTROL

SECURITY MECHANISM

SECURITY MECHANISM

-To provide the services.- A method, tools or procedure for enforcing a security policy.

DATA CONFIDENTIALITY

DATA INTEGRITY

AUTHENTICATION

NONREPUDIATION

ACCESS CONTROL

1,3,4

2,3,7

1,2,3

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SECURITY ATTACKS

PASSIVE ATTACKS

ACTIVE ATTACKS

Interception

Traffic Analysis

Interruption

Fabrication

Replay

Modification

Passive Attack - Interception

Passive Attack: Traffic Analysis

Observe traffic pattern

Active Attack: Interruption

Block delivery of message

Active Attack: Fabrication

Fabricate message

Active Attack: Replay

Active Attack: Modification

Modify message

Handling Attacks

Passive attacks – focus on PreventionEasy to stopHard to detect

Active attacks – focus on Detection and RecoveryHard to stopEasy to detect

System

AttackerAlice

General picture

Security is aboutHonest user (e.g., Alice, Bob, …)Dishonest AttackerHow the Attacker

Disrupts honest user’s use of the system (Integrity, Availability)Learns information intended for Alice only (Confidentiality)

Databases and

data security

It’s your data – are you sure it’s safe?

Network Attacker

Intercepts and controls network communication

Alice

System

Network security

Web Attacker

Sets up malicious site

visited by victim; no control of

networkAlice

System

Web security

OS Attacker

Controls malicious files

and applications

Alice

Operating system security

System

AttackerAlice

Confidentiality : Attacker does not learn Alice’s secrets

Integrity : Attacker does not undetectably corrupt system’s function for Alice

Availability : Attacker does not keep system from being useful to Alice

How Viruses and Worms Spread

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Defending Against Viruses and Worms

Keys to protecting PCsDon’t open e-mails or IM attachments unless

they are expected and have been inspected by antivirus software

Keep up with software patches for your system

Use caution when exploring Web sitesAvoid software from untrusted sourcesStay away from file-sharing networks

WHY INTERNET IS DIFFERENT?

Paper-Based Commerce Electronic Commerce

Signed paper Documents Digital Signature

Person-to-person Electronic via Website

Physical Payment System Electronic Payment System

Merchant-customer Face-to-face Face-to-face Absence

Easy Detectability of modification Difficult Detectability

Easy Negotiability Special Security Protocol

Specific Elements of a Security PolicyAuthentication

Who is trying to access the site?Access Control

Who is allowed to logon and access the site?Secrecy

Who is permitted to view selected informationData integrity

Who is allowed to change data?Audit

What and who causes selected events to occur, and when?

Three components to security

Three perspectivesUser’s point of viewServer’s point of viewBoth parties

Three partsClient-side securityServer-side securityDocument confidentiality

Client-side securityMeasures to protect the user’s privacy

and the integrity of his computerExample technological solutions

Protection from computer viruses and other malicious software

Limit the amount of personal information that browser’s can transmit without the user’s consent

Any others?

Server-side security

Measures to protect the server and the machine it runs from break-ins, site vandalism, and denial-of-service attacks.

Solutions range installing firewall systemstightening operating systems security

measures

Document confidentiality

Measures to protect private information from being disclosed to third parties.

Example risks:

Solutions rangePassword to identify usersCryptography

Tools Available to Achieve Site Security

Encryption Transforms plain text or data into cipher

text that cannot be read by anyone outside of the sender and the receiver. Purpose: to secure stored information to secure information transmission.

Cipher text text that has been encrypted and thus cannot

be read by anyone besides the sender and the receiver

Symmetric Key Encryption DES standard most widely used

Encryption Public key cryptography

uses two mathematically related digital keys: a public key and a private key.

The private key is kept secret by the owner, and the public key is widely disseminated.

Both keys can be used to encrypt and decrypt a message.

A key used to encrypt a message, cannot be used to unencrypt the message

Public Key Cryptography - A Simple Case

Public Key Cryptography with Digital Signatures

Public Key Cryptography: Creating a Digital Envelope

Securing Channels of Communications

Secure Sockets Layer (SSL) is the most common form of securing channels

Secure negotiated sessionclient-server session where the requested

document URL, contents, forms, and cookies are encrypted.

Session key is a unique symmetric encryption key chosen for a single secure session

Securing Channels of Communications

Secure Hypertext Transfer Protocol (S-HTTP)secure message-oriented

communications protocol for use with HTTP.

Virtual Private Networks (VPN) remote users can securely access internal

networks via Point-to-Point Tunneling Protocol (PPTP)

Secure Negotiated Sessions Using SSL

Protecting Networks Firewalls

software applications that act as a filter between a private network and the Internet

Proxy serverserver that handles all communications

originating from or being sent to the Internet, acting as a spokesperson or bodyguard for the organization

Tension Between Security and Other Values

Ease of use Often security slows down processors and

adds significantly to data storage demands. Too much security can harm profitability; not enough can mean going out of business.

Public Safety & Criminal Use claims of individuals to act anonymously vs.

needs of public officials to maintain public safety in light of criminals or terrorists.

Why Care?

Online banking, trading, purchasing may be insecure Credit card and identity theft

Personal files could be corrupted All school work, music, videos, etc. may be lost

Computer may become too slow to run If you aren't part of the solution you are part of the problem

Pwn2Own contest - 2008 Mac (Leopard) fell first via Safari, Vista took time but was

hacked via Flash Player, Ubuntu stood ground.

Upon discovery, vulnerabilities can be used against many computers connected to the internet.

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